Field of the Invention
The present invention relates to an electronic apparatus, an accessory device, control methods therefor, and storage mediums storing control programs therefor, and in particular, relates to a connection-detection control between an electronic apparatus body and accessories, and to a switching control of a communication protocol (a communication system).
Description of the Related Art
An image pickup apparatus, such as a digital camera, is one of electronic apparatuses. Conventionally, when a body of an image pickup apparatus, such as a camera body of a digital camera, is connected to accessories, such as a flash device and an interchangeable lens unit, connection of communication terminals of the camera body and the accessories is detected. Then, when detecting the connection, the camera body communicates with the accessories. The camera body determines that the connection is abnormal when there is no reply from the accessories or when reply data has anomalies.
Furthermore, when a communication protocol (i.e., a communication system) is changed, it is determined whether a post-change communication method (a new communication method) is acceptable by communicating in a pre-change communication method (an old communication method). If acceptable, the communication method is changed to the new communication method.
For example, Japanese Laid-Open Patent Publication (Kokai) No. H2-63030 (JP H2-63030A) discloses the following technique. An interchangeable lens unit is provided with first, second, and third information transmission units that have different amount of information. When the interchangeable lens unit is connected to a camera body, the interchangeable lens unit selects one information transmission unit corresponding to an ability of the camera body and communicates with the camera body. In this publication, when it becomes clear that the camera body has an ability corresponding to the second or third information transmission unit that has large amount of information during the communication using the first information transmission unit that has small amount of information, the interchangeable lens unit starts communicating with the camera body using one of the second and third information transmission unit.
However, the camera disclosed in the above-mentioned publication needs to determine reply contents transmitted to the camera body from the interchangeable lens after connection in order to check the connection between the interchangeable lens unit and the camera body. Accordingly, the camera body needs to verify accuracy of the determination and takes time for the determination process.
Furthermore, when a communication method is changed from an old communication method (first communication method) to a new communication method (second communication method), it is necessary to check whether the new communication method is acceptable by communicating in the old communication method before changing to the new communication method, which takes time for changing.